1. Field of the Invention
The present invention relates to a method and devices for the production of printed graphic patterns which project an image that follows the motion of the observer, irrespective of its speed, when placed in the common focal plane behind a lenticular plate made of a plurality of cylindrical converging lenses, arranged side by side and parallel to each other. If the panel composed of the two objects, that is, the properly prepared graphic pattern and the lenticular plate, is long enough, a movie picture can be exhibited to the observer travelling along the principal direction.
2. Description of the Related Art
There is a number of optical effects and devices associated with the combination of a graphic pattern and a lenticular screen made of a plurality of cylindrical converging lenses arranged side by side, parallel each other, and with a common focal plane.
A well-known class of this sort of optical apparatuses is derived from the early invention of J. S. Curwen, U.S. Pat. No. 1,475,430, issued in Feb. 27, 1922. These devices are used either to exhibit a sequence of a limited number of pictures that change when the viewing angle relative to the apparatus varies, or to display stereoscopic images. The exhibition of a short animation, or the stereoscopic image of a rotating object, are direct applications of the same basic idea. Examples of related issued patents are U.S. Pat. Nos. 2,832,593, 4,506,296, 4,542,958, 4,663,871 and 4,944,572.
This first class of display panels are not related to the present invention, but it was mentioned and is briefly described in the next paragraph just to stress the essential difference they have with a second class of devices, which do relate with the invention and are explained later on.
What the devices of the first kind have in common is a graphic pattern composed by a limited number n of lineated images, all them made of the same number of parallel straight lines, as high as necessary to have an acceptable graphic resolution in the direction transverse to the straight lines forming the picture. The graphic pattern is an ordered mixture of the lines of all the lineated figures, which locates first the first lines of all the figures, in the correlative order chosen for the n images of the set, next come the second lines in the same order, and so on. The optical screen is placed in front, at the focal distance of the cylindrical lenses, with the lenses parallel to the pattern lines. Each lens of the screen has a set of n lines behind, one from each of the n images. Because of the high transverse optical amplification, the observer will see only one line in each lens, the rest of the lines falling beyond the limits of the lens field. The observer is usually at a distance much larger than the dimensions of the display panel and, as the viewing angular position with respect to the plane of the screen is almost the same for all lenses, the lines displayed by all them correspond to the same figure. Hence the global effect is that the screen selects and exhibits the lines of only a single image, which becomes displayed. This selective effect is governed by the angular position of the observer. As this angle changes the displayed image changes as well. If each pair of contiguous pictures of the set correspond to the right and left eye vision of the same object, respectively, the panel will display stereoscopic images.
The present invention is related to a different class of exhibiting panels constituted by a graphic pattern and a lenticular plate made of a plurality of cylindrical converging lenses arranged side by side and parallel to each other, with a common focal plane. This second kind of exhibiting panels is much less known than the first one and yields a very different optical effect. The essential differences are in the graphic structure of the printed pattern, the function fulfilled by the eyes of the observers and some practical requirements on the dimension of the elements of the system. The seminal patent was issued to A. J. L. Ossoinak, U.S. Pat. No. 2,833,176, in May 6, 1958. A further application was patented in 1971 by E. J. Smith, U.S. Pat. No. 3,568,346. Exhibiting panels of this second class are preferably very long in the direction along the plate transverse to the geometrical axis of the cylindrical lenses or, equivalently, transverse to the generatrix of the cylindrical surfaces of the lenses. Hereafter the transversal direction will be referred to as the principal direction. Any person facing the panel will see an image directly in front, no matter the position. If the viewer moves along the principal direction the image will always stay in front, following the motion of the observer, irrespective of its speed. The system is particularly suited for exhibiting movie pictures to moving observers. Examples are train or tramway passengers, with the display panel installed along the vehicle path, and people in mechanical escalators or corridors.
However, during the life of Ossoinak patent, its commercial application to exhibit movie pictures to passengers of public transportation was prevented by the high production costs of the graphic patterns. The present invention takes advantage of the more recent technology to solve this inconvenience.
The graphic pattern is located in the focal plane behind the lenticular plate and the viewer is in front of the plate. The pattern is composed of a series of printed figures, in general repeated identically Nrep times. Each of the printed figures is a copy of the same picture that will be exhibited but compressed in the principal direction, that is, the dimension of the lenticular plate transverse to the geometrical axis of the cylindrical surfaces of the lenses. The graphic compression is such that the distorted figures have at most the same width of a cylindrical lens. This way, each cylindrical lens has behind it a complete figure of the graphic pattern. FIG. 1 shows the construction of the system and how it works in a subjective way. FIG. 2 shows a further explanation of the optical bases of the second kind of devices.
The system will work equally well if the lenticular plate is made of a two-dimensional array of spherical lenses, instead of a linear succession of cylindrical lenses. However, for most applications the use of spherical lenses is less practical because the displayed picture will follow the viewer's displacements in both dimensions of the panel (along the principal direction and along the perpendicular to the principal direction). This may be a problem if the panel is not large enough in the not principal direction. Nonetheless, two-dimensional graphic patterns and lenticular plates of spherical lenses are considered as an extension of the cylindrical lenticular plates.
The exhibiting panel displays the picture contained in the fringes of the graphic pattern with the principal dimension (for example, width) expanded to the normal size in relation to the other dimension (for example, height) of the picture. The observed picture follows the motion of a viewer moving at any speed in the principal direction. If after each Nrep repetitions of a compressed image in the graphic pattern the image is changed to the next frame of a cinematographic sequence, the moving observer will see an animated scene in the panel.
The present invention is concerned with the production of graphic patterns for the practical use of the just described class of devices for exhibiting movie pictures to moving people by means of a large apparatus at rest, with reasonable costs.
The present invention uses a combination of powerful computers, digital picture processing, electronic devices for the efficient conversion of movies in video or film substrates into sequences of digital images, and large high resolution printing machines for digital images.